Interlaboratory comparison for heat transfer coefficient identification in hot stamping of high strength steels

2010 ◽  
Vol 3 (S1) ◽  
pp. 817-820 ◽  
Author(s):  
P. Bosetti ◽  
S. Bruschi ◽  
T. Stoehr ◽  
J. Lechler ◽  
M. Merklein
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Interlaboratory Comparison ◽  
Hot Stamping ◽  
High Strength Steels ◽  
High Strength ◽  
Coefficient Identification

Characterization of Heat Transfer Coefficients of Tool Materials and Tool Coatings for Hot Stamping of Boron-Manganese Steels

2010 ◽  
Vol 438 ◽  
pp. 81-88 ◽  
Author(s):  
Michael Wieland ◽  
Marion Merklein
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Hot Stamping ◽  
High Strength Steels ◽  
High Strength ◽  
Tool Steels ◽  
Transfer Coefficients ◽  
Element Analysis ◽  
Coated Tool

One characteristic of hot stamping of ultra high strength steels is the high wear rate of the used tools which leads to shorter tool life. Coatings improving wear resistance can increase the lifetime of the used tools but process relevant data such as the heat transfer capability of coated tool steels are missing. Within this paper the heat transfer capabilities of coated tool steels for the hot stamping processes are determined. Therefore different coating systems based on AlCrN are applied on the tool steels and the pressure dependent heat transfer coefficient is determined using process relevant conditions. As semi-finished blank the hot stamping steel 22MnB5 with an aluminum-silicon pre-coating is used. With respect to a finite element analysis of the forming operation of the hot stamping process the heat transfer coefficient represents an important input data for the process layout.

High Temperature Heat Transfer During Hot Forming Die Quenching of Boron Steel

2013 ◽  
Author(s):  
Etienne Caron ◽  
Kyle J. Daun ◽  
Mary A. Wells
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cooling Rate ◽  
Hot Stamping ◽  
High Strength ◽  
Hot Forming ◽  
Boron Steel ◽  
Steel Blank ◽  
Die Quenching

Distributed mechanical properties can be obtained in ultra high strength steel parts formed via hot forming die quenching (HFDQ) by controlling the cooling rate and microstructure evolution during the quenching step. HFDQ experiments with variable cooling rates were conducted by quenching Usibor® 1500P boron steel blanks between dies pre-heated up to 600°C. The heat transfer coefficient (HTC) at the blank / die interface, which is used to determine the blank cooling rate, was evaluated via inverse heat conduction analysis. The HTC was found to increase with die temperature and stamping pressure. This heat transfer coefficient increase was attributed to macroscopic flattening of the boron steel blank as well as microscopic deformation of surface roughness peaks. At the end of the hot stamping process, the HTC reached a pressure-dependent steady-state value between 4320 and 7860 W/m2·K when the blank and die temperatures equalize.

The Study of Heat Transfer Coefficient during Cooling Plates of High Strength

2015 ◽  
Vol 220-221 ◽  
pp. 760-764
Author(s):  
Marcin Janik ◽  
Tomasz Garstka ◽  
Aneta Krzyżańska ◽  
Marcin Knapiński ◽  
Anna Kawałek
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Strength ◽  
Accelerated Cooling ◽  
Plastic Properties ◽  
Cooling Intensity ◽  
Hot Rolled ◽  
The Impact ◽  
Selection Of

Nowadays methods of hot-rolled sheets should ensure high mechanical and plastic properties of sheets, in-line rolling. Such technologies require application of devices for accelerated cooling of a band after last deformation. The essential thing in this process is selection of an appropriate positioning of the cooling intensity. The paper presents results of the cooling intensity for the selected air-water nozzle. On the basis of the results, the map of distribution of heat transfer coefficient for the nozzle to the surface of the cooling was performed. These tests were carried out for different settings of water and air. The research was carried out for high-strength steel. The obtained results allow executing of computer simulation of the impact of cooling intensity on the final product’s structure.

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